The present disclosure relates to data storage devices. In particular, the present disclosure relates to wear leveling techniques for extending the usable lives of storage devices, such as flash-based storage devices.
Data storage devices based on flash-based technologies are becoming increasingly popular for the storage of data. This is primarily due to their robust architecture, low power consumption, and compact designs. A common use of flash-based storage devices is in combination with computer interfaces, such as universal serial bus (USB) interfaces, to provide fast-access flash drives that can read and write data in a manner that is convenient for users. Such drives typically have storage capacities up to about 64 gigabytes, which is ideal for storing and transferring data between different computer systems. Additionally, many industries are focusing on larger, more permanent flash-based storage devices to replace or supplement hard disks in a variety of computer systems. These solid-state drives desirably have large storage capacities and may function as the primary drives of the computer systems for retaining operating systems, applications, documents, and other data files.
Flash-based storage devices include large numbers of data blocks for writing and reading data. Data may also be rewritten by erasing the previous version of the data and writing the new version to the same or different data blocks. However, erasure of data from a given data block typically requires erasure of the entire data block, regardless of whether all of the data within the data block needs to be erased. Furthermore, the data blocks in a flash-based storage device have limited numbers of erasure counts before failing, which limits the overall life of the storage device. Accordingly, the life of a flash-based storage device is typically limited to the available erasure counts of the data blocks.
Common techniques for increasing the usable lives of storage devices involve wear leveling techniques, where the data block erasures are distributed in a uniform manner. This allows the erasure counts of the data blocks to rise in a substantially even amount, thereby increasing the overall number of available erasures. However, larger storage devices, such as solid state drives, may include static data that is not commonly erased or rewritten (e.g., operating systems and computer applications). Current wear leveling techniques that attempt to maintain uniform or near uniform wear levelness in these storage devices actually induce additional data block erasures into the given devices for the sake of maintaining the uniform wear levelness. Thus, there is an ongoing need for wear leveling techniques that address such concerns and further increase the useful lives of storage devices, such as flash-based storage devices.